Life cycle assessment of hydrotreated vegetable oil from rape, oil palm and Jatropha

Artikel i vetenskaplig tidskrift, 2011

A life cycle assessment of hydrotreated vegetable oil (HVO) biofuel was performed. The study was
commissioned by Volvo Technology Corporation and Volvo Penta Corporation as part of an effort to gain
a better understanding of the environmental impact of potential future biobased liquid fuels for cars and
trucks. The life cycle includes production of vegetable oil from rape, oil palm or Jatropha, transport of the
oil to the production site, production of the HVO from the oil, and combustion of the HVO. The functional
unit of the study is 1 kWh energy out from the engine of a heavy-duty truck and the environmental
impact categories that are considered are global warming potential (GWP), acidification potential (AP),
eutrophication potential (EP) and embedded fossil production energy. System expansion was used to
take into account byproducts from activities in the systems; this choice was made partly to make this
study comparable to results reported by other studies. The results show that HVO produced from palm
oil combined with energy production from biogas produced from the palm oil mill effluent has the
lowest environmental impact of the feedstocks investigated in this report. HVO has a significantly lower
life cycle GWP than conventional diesel oil for all feedstocks investigated, and a GWP that is comparable
to results for e.g. rape methyl ester reported in the literature. The results show that emissions from soil
caused by microbial activities and leakage are the largest contributors to most environmental impact
categories, which is supported also by other studies. Nitrous oxide emissions from soil account for more
than half of the GWP of HVO. Nitrogen oxides and ammonia emissions from soil cause almost all of the
life cycle EP of HVO and contribute significantly to the AP as well. The embedded fossil production energy
was shown to be similar to results for e.g. rape methyl ester from other studies. A sensitivity analysis
shows that variations in crop yield and in nitrous oxide emissions from microbial activities in soil can
cause significant changes to the results.